CNC machining questions - Lateral-g Forums

Mike Hall · #1 11-10-2006, 10:56 PM

I have some parts that will need to be turned on a CNC lathe and then finished up on a CNC mill. Im looking for any ideas on what this kind of machine work will cost me. Here is one part which is T6 aluminum and is around 4.5" diameter.

Thanks
Mike

Blown353 · #2 11-11-2006, 12:00 AM

The programming will cost more than the actual machine time if you have to have it CNC'd.

The part looks simple enough to make judging by the views; it would be a single setup on an NC lathe with live tooling.

Without knowing all your features/dimensions, it looks like I could make it manually too, my hunch would be about 2 hours if I did it (and I'm a slowpoke engineer who moonlights in the shop)-- typical shop rate around here is $100/hr.

You might want to try doodling it up at emachineshop.com and see what they quote for a price.

Never expect a reasonable price if you're only going to buy one or two pieces, setup time/charges factor into the price much more heavily for small runs.

Hopefully Steevo chimes in, I *think* he might have some machine shop experience.

Mike Hall · #3 11-11-2006, 12:22 AM

Thanks for the input. I will be needing 6 of these per project which at this time is only one. LOL I can get the set of 6 for $370 which may be the best way to go. This is only one of the parts I would need machined. I have all sorts of parts made from 4130 to 6061. I think your right that most could be machined without CNC. Im just getting an idea if I should just buy all these parts or get them machined.

Mike

Blown353 · #4 11-11-2006, 12:27 AM

Quote:

Originally Posted by Mike Hall

Thanks for the input. I will be needing 6 of these per project which at this time is only one. LOL I can get the set of 6 for $370 which may be the best way to go. This is only one of the parts I would need machined. I have all sorts of parts made from 4130 to 6061. I think your right that most could be machined without CNC. Im just getting an idea if I should just buy all these parts or get them machined.

Mike

The programming cost up front might be somewhat expensive but if you anticipate repeated runs it will probably pay for itself. Have them quote multiple quantities and work out the break even point. If you think you're going to want more in the future the cheapest way will definately be to have them all made at the same time, saves on setup costs.

**Steve Chryssos** · #5 11-11-2006, 05:59 AM

http://www.twistmachine.com/customshop/

Everything Blown says is true, but your expense can be minimized by providing detailed prints--preferably with tolerances. Looks like you're ahead of the game. Give us a call on Monday.

**Steve68** · #6 11-11-2006, 12:03 PM

Would save time and effort for the machinist to have all the dimensions on the print or sidebared,

Blown353 · #7 11-11-2006, 08:33 PM

Quote:

Originally Posted by streetfytr68

http://www.twistmachine.com/customshop/

Everything Blown says is true, but your expense can be minimized by providing detailed prints--preferably with tolerances. Looks like you're ahead of the game. Give us a call on Monday.

Make Steve happy and his life easy... TP .001 on your radially located holes, concentricity under .0002, hole diameters +/- 0.0001, surface finish 5RMS or smoother, and then give him something fun to work with like Hastelloy.

(I think I can hear him screaming now.)

PhaseShift · #8 11-19-2006, 02:33 AM

I am way late to the party here-

Unless I am not seeing something in the drawing, I would say that you do not need CNC work on that part at all. Especially if the inside radius on the turned area is not a critical feature.

First setup the part in a manual mill with an indexer, drill your holes and do the counter bores. , then you can finish the turning operations on a lathe, probably do it between centers and at the end of the process, part off the smaller end.

If we made that in our shop and were only making a few of them, I would have our guys run it on manual equipment. If I were doing say, 50 or so, still stick with the lathe (depending on the tolerances and surface requirements) and do the holes and counterbores with a CNC simply because it would be easy to do them fast.

Phase

**Steve Chryssos** · #9 11-19-2006, 09:41 AM

Quote:

Originally Posted by Blown353

Make Steve happy and his life easy... TP .001 on your radially located holes, concentricity under .0002, hole diameters +/- 0.0001, surface finish 5RMS or smoother, and then give him something fun to work with like Hastelloy.

(I think I can hear him screaming now.)

Doesn't bother me one bit. I get all the crappy jobs like driving cool cars and flying around the country. It's John Schilling's temper that you need to worry about.